C++核心準則R.12:立即將顯式分配的資源交給資源管理對象​

• 2020 年 3 月 31 日
• 筆記

R.12: Immediately give the result of an explicit resource allocation to a manager object

R.12:立即將顯式分配的資源交給資源管理對象

Reason(原因)

If you don't, an exception or a return may lead to a leak.

如果不這樣做，發生異常或者返回操作時可能會引發泄露。

Example, bad(反面示例)

void f(const string& name)  {      FILE* f = fopen(name, "r");            // open the file      vector<char> buf(1024);      auto _ = finally([f] { fclose(f); });  // remember to close the file      // ...  }  

The allocation of buf may fail and leak the file handle.

如果分配buffer失敗（拋出異常，譯者注）就會導致文件句柄的泄露。

Example(示例)

void f(const string& name)  {      ifstream f{name};   // open the file      vector<char> buf(1024);      // ...  }  

The use of the file handle (in ifstream) is simple, efficient, and safe.

(使用ifstream管理)文件句柄的用法簡單、高效而且安全。

Enforcement(實施建議)

• Flag explicit allocations used to initialize pointers (problem: how many direct resource allocations can we recognize?)
• 標記使用顯式分配的資源初始化指針的情況(問題是：我們能夠識別出多少直接分配資源的情況？)

原文鏈接：

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#r12-immediately-give-the-result-of-an-explicit-resource-allocation-to-a-manager-object